Original reply from user NO-STOCK
Yes. As long as you can upload the QR image file to a website or web server, you should be able to reference it using HTML code. The guy who runs this website explains some of it in this blog post. He also sells pre-made packing slips and builds custom designs.
This does not appear to work correctly but the image url is correct.
<img src="https://cdn.shopify.com/s/files/1/2447/5049/files/QRCodeTOList.jpg" height="90px" width="90px">
Not sure why. I've tried directly in the packing slip and Packing Slip Footer. It works when I use the URL here too.